733
FXUS65 KFGZ 310946
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
246 AM MST Fri Jul 31 2026

.SYNOPSIS...Somewhat diminished monsoonal activity is expected
through this weekend as high pressure builds overhead. Very hot
temperatures are expected, reaching the warmest readings so far
this year. Monsoon moisture is then expected to start moving back
into the region next week as the high moves into a more favorable
position.

&&

.DISCUSSION...Strong high pressure will shift westward and build
over Arizona today. Monsoon activity will continue to diminish
due to subsidence under the ridge plus drier air gradually
working into region. However, there remains enough moisture and
instability for isolated to scattered showers and thunderstorms
today. Coverage will be mostly restricted to the high terrain
from Flagstaff southward, and will be maximized around the White
Mountains. With very slow storm motion and PW still near the 75th
percentile, a low-end flash flood threat over burn scars remains a
factor. This somewhat suppressed period of monsoonal activity is
forecast to continue through at least the weekend. Showers and
thunderstorms will not fully shut off each day, but remain
isolated to scattered with the best coverage in the White
Mountains.

Outside of storm activity, the primary hazard over the next few days
will be heat. With the declination in moisture, above normal heights
at 500mb will lead to the warmest temperatures of the year so far
for all of northern AZ. As a result, a variety of heat headlines
will be in effect. An Extreme Heat Warning for the Grand Canyon
below 4000 ft will remain in effect until Sunday with daytime
temperatures up to 110-115 F. Additional Extreme Heat Warnings will
be in effect today through Sunday for Glen/Marble canyon and low
elevation areas south of the Mogollon Rim, where temperatures
will approach or exceed 110 F. Valleys north of the Rim will have
a Heat Advisory on Saturday and Sunday, with daytime temperatures
up to 100-105 F.

By the early to middle part of next week, ensemble guidance is
leaning towards the high weakening and shifting east. This would
allow monsoonal activity to increase again. There is still some
uncertainty on the exact timing and nature of this transition, and
there is potential that heat headlines will be extended past Sunday.
Right now the forecast calls for continued hot temperatures with
diminished monsoonal activity on Monday and Tuesday.

&&

.AVIATION...Friday 31/06Z through Saturday 01/06Z...VFR conditions.
ISO -SHRA/-TSRA mainly INVOF a KFLG-KJTC line from 19Z to 03Z. Gusty
outflow winds 30-40 kts possible in and around TS. Otherwise, VRB
winds 5-10 kts.

OUTLOOK...Saturday 01/06Z through Monday 03/06Z...VFR conditions.
ISO -SHRA/-TSRA 18Z-03Z each day, mainly INVOF KSOW/KJTC. Gusty
outflow winds 30-40 kts possible in and around TS. Otherwise, VRB
winds 5-10 kts.

&&

.FIRE WEATHER...Today and Saturday...Very hot, with the warmest
temperatures of the year so far. Isolated to scattered showers
and thunderstorms each afternoon/evening over the high terrain
Flagstaff eastward, best coverage in the White Mountains. Winds
generally west to northwest at 5-15 mph. Minimum RH values as low
as 10-15% in the deserts, 15-25% mountains.

Sunday through Tuesday...Very hot temperatures again on Sunday, with
a gradual cooling trend thereafter. Isolated showers and storms over
the high terrain of eastern AZ on Sunday and Monday, with coverage
increasing and expanding westward on Tuesday. Daytime winds
generally southwest to west at 5-15 mph each day.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning from 10 AM MST /11 AM MDT/ this morning to
8 PM MST /9 PM MDT/ Sunday for AZZ005-018-037-038.

Extreme Heat Warning until 8 PM MST Sunday for AZZ006.

Heat Advisory from 10 AM MST /11 AM MDT/ Saturday to 8 PM MST /9
PM MDT/ Sunday for AZZ009-010-012>014-040.

&&

$$

PUBLIC...Lewandowski
AVIATION...Humphreys
FIRE WEATHER...Lewandowski

For Northern Arizona weather information visit
weather.gov/flagstaff